1. Field of the Invention
The present invention relates to an image-displaying device, method and system. More particularly, the invention relates to an image-displaying method and system that display a stereoscopic image by emitting a light beam representing an image for the left eye and a light beam representing an image for the right eye.
2. Description of the Related Art
Systems that display a stereoscopic image by projecting an image for the left eye and an image for the right eye on a screen using a single image display device have been proposed. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2007-271828 discloses a system that projects a stereoscopic image using a split mirror. A display area of a display device is substantially divided into two image areas, i.e., an area for an image for the left eye and an area for an image for the right eye. Light beams representing the displayed images for the left and right eyes are split by a split mirror. The split light beams are then projected onto a screen in a superimposed manner via optical filters having different optical properties to form a stereoscopic image. JP-A-2005-65055 discloses a system that displays image content as a plane image on the basis of an input image signal representing a two-dimensional image content. JP-A-2005-65055 also discloses a system that displays an image content as a three-dimensional image on the basis of an input image signal representing a three-dimensional image content. An optical filter is used to, for example, switch polarization directions of light beams representing the image for the right eye and one image for the left eye.
Such an optical filter used to display a stereoscopic image, however, may cause changes in the properties of an image to be displayed.
For example, if a stereoscopic image is to be displayed using a wavelength division system, the wavelength of an emitted light beam is limited by the optical filter. FIGS. 1A to 1D illustrate functions of wavelength division filters for the left eye and for the right eye. FIG. 1A illustrates intensity of light beams incident to the wavelength division filters for the left eye and for the right eye as a model. FIG. 1B illustrates a filter characteristic of the wavelength division filter for the left eye. FIG. 1C illustrates a filter characteristic of the wavelength division filter for the right eye.
The light beam processed by the wavelength division filter for the left eye is divided into color components for the left eye shown in FIG. 1D. The light beam processed by the wavelength division filter for the right eye is divided into color components for the right eye shown in FIG. 1D.
When a plane image is to be displayed, a color space is converted so that an image of desired color can be displayed on the basis of an emitted light beam having the color components shown in FIG. 1A.
FIGS. 2A and 2B illustrate changes in property of a displayed plane image and a displayed stereoscopic image. Image display devices covert a color space so that an image to be displayed may have a desired color when a plane image is to be displayed on the basis of, for example, an image signal representing a two-dimensional image content, i.e., when a light beam having the color components shown in FIG. 1A is emitted. The image to be displayed may therefore have a desired color, as shown, for example, in FIG. 2A. A chromaticity point of the image shown in FIG. 2A herein is a position PC-2D in an xy chromaticity diagram shown in FIG. 3.
Next, when a stereoscopic image is to be displayed on the basis of an image signal representing a three-dimensional image content, a wavelength of a light beam passing through a wavelength division filter is limited as shown in FIG. 1D. Such limitation on the wavelength may cause changes in color or brightness of the images for the left eye and for the right eye as shown in FIG. 2B. The chromaticity point of the image for the left eye shown in FIG. 2B may be shifted to, for example, a position PC-3DL of FIG. 3. The chromaticity point of the image for the right eye shown in FIG. 2B may be shifted to, for example, a position PC-3DR of FIG. 3.